engine bog on acceleration

[tricky12]

Hi folks i have an 88 carb turbo (X180) I know im in the G car room but there are a lot more carb turbos in here or seem to be, so i thought i would give you guys a bash.

my car starts runs and idles and will rev happily on the drive however when i drive the car and try to accelerate eg junctions and traffic lights the car bogs and often will have to pull over and try to pick up the revs so as to in effect clear itself. This is not a nice feeling and is a bit nerve racking.

From the list of things done you can see i am now running out of things to check.

New plugs and leads

new dizzy cap and rotor arm

new fuel filter

new vaccum hoses

checked fuel pressure ok

carbs overhauled new gaskets etc

It was suggested that it sounds like over fueling so last weekend i turned the mixture screws in a quarter and went for a short blast only giving gentle throttle and things seem better so i turned the mixture in again and took the car out again and things were better still, so i did this a third time and still seemed to get an improvement. which is where i am at now and the car feels a bit more driveable but still no quite as i would expect an Esprit Turbo.

SO PLEASE HELP !!

[910Esprit]

Overfueling on a fixed jet carburettor would be unusual - assuming its got the correct jets fitted. Its much more common to run weak on transition from idle circuits to mains - circa 3000 rpm.

What do the sparkplugs look like?

[trackmagic]

My guess ....... if it revs fine and no excessive black smoke under no load (sitting) but can't make power under load (driving) I would have a look at the ignition system. Possible weak coil or amplifier.

Like Steve suggested, give the plugs a look.

Good luck,

Jeff

[USAndretti42]

Could it be the throttle pumps? While it would be unlikely for them both to fail at the same time one could have failed without you realizing and now the other has gone. Check the diaphragms.

[cly_mitchell]

Stupid question, but are you making boost? If you lean the carbs and it runs better, then you may need more air. You could also have an advance problem, mechanical and or vacuum. Did you check fuel pressure while running under load?

cheers

clay

[tricky12]

Thanks for suggestion. to answer a couple of you replies

throttle pumps are ok the carbs have been overhauled

vacuum appeared to be ok and advancing when timming strobe was on checking the timming

i am also achieving boost ok

once i can get revs on the car will fly its just low down that i have a problem

[jonwat]

The mixture screws only adjust the mixture of the idle jets which are no longer used once the throttle is more than a few millimetres open - use a colour tune the check & adjust your idle mixture.

The accelerator pump circuit is there to add extra fuel for acceleration. It is required because air weighs a lot less than fuel & when the throttle is suddenly opened the volume of air going in to the engine increases leaving the fuel behind, so there is a big flat spot caused by the mixture weakness until the fuel catches up. The pump jet fills in the hole when this happens by pumping in extra fuel until the normal flow of fuel suits the rate of air demand.

Assuming the carbs are balanced correctly (did you balance them after rebuilding & refitting??) it sounds like the pump jets aren't working correctly.

Cheers,

John W